I got your point but most probably there's no setting that can change this even that you're with the latest FW v1.3.2 for AX55 v1. Here should come the Easymesh ethernet backhaul but I suppose it's...

@eplante When Smart Connect is on the RE will decide which band is best for a particular client device (Band steering) - you can't interfiere this process.

@eplante Which FW release do you have on AX55 v1 and do you have its Smart Connect feature on ?

@christoskelton Get the ethernet cable from the AX6000 kit and use it to connect you computer to AX6000 LAN port. Any Cat 5E will suffice to connect AX6000 LAN port. Here's how to find your AX6000 IP...

@MikeB75 Both BE800 and BE550 support Easymesh ethernet backhaul - details. Your BE550 should be in wireless router mode (factory reset) to configure this - here's a guide.

@christoskelton Post your network status screenshot: along with its ethernet port status: